预制装配部分外包混凝土组合梁受弯承载力试验研究

为降低大跨、重荷建筑的建设工程造价，提出一种预制装配部分外包混凝土组合梁(PPECB)。设计了7根受弯组合梁试件进行静力试验以研究其受弯性能，考虑浇筑方式、工字钢翼缘厚度、混凝土强度等级、配箍形式对其承载力的影响，研究破坏模式、应变发展和受弯承载力，明确预制装配部分外包混凝土组合梁的破坏机制。结果表明：7根组合梁表现出相似的受力性能，均发生弯曲破坏；PPECB开裂荷载与整浇部分外包混凝土(PEC)梁近似，屈服荷载、峰值荷载略低于整浇PEC梁；随混凝土强度等级的提高，PPECB开裂及屈服荷载增大，但峰值荷载无明显提升；PPECB开裂、屈服、峰值荷载随工字钢翼缘厚度增加而提高；配箍形式对PPECB开裂荷载无明显影响，拉杆形式PPECB屈服、极限荷载均低于半封闭箍筋形式PPECB。给出了预制装配部分外包混凝土组合梁的受弯承载力计算公式，其计算结果与试验结果吻合较好。

Experimental study on flexural bearing capacity of prefabricated and assembled partially encased composite beams

In order to reduce the construction cost of large span and heavy load buildings, a type of prefabricated and assembled partially encased concrete composite beams (PPECBs) was proposed in this paper. In order to investigate its flexural behavior and the influence of fabrication method, flange thickness of I-shaped steel section, concrete strength grade and stirrup form on the bearing capacity, seven flexural specimens were designed for static test. The failure mode, strain development and flexural bearing capacity were mainly studied, and the failure mechanism of partially prefabricated and partially enclosed concrete composite beams was clarified. The results show that the seven specimens exhibite similar mechanical behavior and all of them suffer from bending failure. The cracking bearing capacity of PPECBs is similar to that of partially encased concrete(PEC) beams, and its yield and ultimate bearing capacities are slightly lower than those of PEC beams. With the increase of concrete strength grade, the cracking and yield capacities of PPECBs both increase, but the ultimate bearing capacity does not increase significantly. The cracking, yield and ultimate bearing capacities of PPECBs increase with the flange thickness. The form of stirrups has no obvious influence on the cracking bearing capacity of PPECBs. The yield and ultimate bearing capacities of tie rod PPECBs are lower than those of semi-closed stirrup PPECBs. The formulas for calculating the flexural bearing capacity of prefabricated and assembled partially encased concrete composite beams are given, and the calculated results are in good agreement with the experimental results.